This disclosure relates generally to filter assemblies which separate water from a flow of fluid such as diesel fuel or hydraulic fluid. More particularly, this disclosure relates to systems and methods for removing water from the water collection chamber of a filtration system.
In fuel delivery systems for which the present disclosure has application, it is critical that water and particulates be removed from the fuel supply prior to pressurization and delivery to the internal combustion engine. A pre-filter and/or fuel filter is commonly disposed between the fuel reservoir or fuel tank and a lift pump to separate water and particulates from the fuel. In this configuration, the fuel filter is disposed on the suction side of the pump. Consequently, the fuel filter is essentially under a vacuum when the associated vehicle is operating. In many conventional systems, water accumulates in a collection chamber at the bottom of the fuel filter and is regularly manually removed.
Fuel filter assemblies are typically arranged to take advantage of the fact that water has a higher specific gravity than diesel fuel and will tend to fall to the bottom of the assembly and accumulate in a chamber arranged to collect separated water. The filter assembly includes a fluid flow path for separated water to descend from the filtration chamber to a water accumulation chamber arranged below the filtration chamber. As long as these fluid flow paths remain open, the water accumulation chamber is exposed to the same low pressure as the filtration chamber. When the vehicle is not operating, opening a drain valve in the water accumulation chamber allows ambient air to enter and water to flow out by force of gravity. Such an arrangement is not practical when the vehicle is operating, because opening the drain valve would interrupt the suction of the lift pump and stop fuel delivery to the engine.
A number of systems and methods have been proposed to automatically drain water from the collection chamber of a fuel filter assembly. Many of the proposed automatic systems require that the engine be off and/or inoperative while the water is removed from the collection chamber to avoid the pressure differential and fuel interruption issues discussed above. Some water drain systems employ solenoids and elaborate circuitry for operation in order to drain water. Among other deficiencies of prior proposals are water removal systems that are complicated and relatively expensive to implement.
The disclosed apparatus, systems and methods also have applicability in hydraulic fluid systems, such as those employed on construction equipment, agricultural equipment, and the like. Hydraulic fluid is exposed to moisture, which can become mixed with the fluid and can result in corrosion, growth of organisms that foul the equipment, and other kinds of damage. Hydraulic fluid is filtered to remove particulates, and filter assemblies constructed for that purpose can be modified according to the disclosure to incorporate automatic water removal as described below.